A machining facility called a “machining system” or a “machining cell” is a system for conveying and changing workpieces between at least one machine tool, such as machining center, lathe, grinding machine or electro-discharge machine, and a workpiece placing location called a “setup station” or “stocker” so as to facilitate machining of workpieces. There is the method of using a robot or a manipulator to directly convey workpieces or convey pallets having workpieces mounted thereon.
Japanese unexamined Parent Publication No. 59-107833 discloses a handling robot which loads and unloads a workpiece between a spindle of a lathe and a conveyor unit and performs the loading and unloading of the workpiece on and from the lathe automatically.
Japanese Patent Publication (B2) No. 3-51545 discloses a pallet conveying robot which conveys a pallet having a workpiece mounted thereon between a workpiece station and a table of a machine tool. In the past, a robot having one arm was used to grip an old pallet mounted on a table of a machine tool and convey it to a workpiece station, then grip a new pallet on the workpiece station and convey and mount it to the table of the machine tool. Therefore, the conveyance efficiency was poor. However, this invention solves this problem and enables a plurality of pallets to be efficiently conveyed.
Japanese Utility Model Publication No. 5-46834 discloses a setup system for enabling a sub-pallet having a workpiece mounted thereon to be automatically mounted and dismounted on and from a main pallet and feeding and discharging workpieces to a main pallet conveyor system. In the past, a workpiece was mounted and dismounted on and from an angle plate on a main pallet, and therefore the efficiency of the setup work was poor. However, this invention solves this problem and enables workpieces set-up in advance to be automatically mounted on angle plates in the setup station and thereby improves the work efficiency.
In the prior art described in Japanese Unexamined Patent Publication No. 59-107839, the body of a handling robot is fixed to a base of a lathe and the motion of the arm about three rotational axes and the motion along one linear movement axis can be used to convey and mount a workpiece, placed on a conveyor unit facing upward, on a horizontally oriented spindle of the lathe while changing the direction. Further, it is possible to reverse the orientation of the workpiece and mount it on the spindle. At the front end of the arm, it is possible to detachably mount two or more types of hands which can be changed according to the shape and weight of the workplaces. In this mode, since the workpiece is directly gripped by the robot hand and workpieces come in various shapes and sizes, it is necessary to change two or more types of hands. Therefore, there is the problem that it is necessary to prepare a plurality of hands and prepare a plurality of hand operating programs.
The pallet conveying robot of the prior art described in Japanese Patent Publication (B2) No. 3-51545 has a swiveling member, rotating member, sliding member, and a pair of independently swivelable arms (first arm and second arm). It discloses a configuration wherein motion about four rotational axes and motion along one linear movement axis are used to grip a pallet of a workpiece station placed in a state with the workpiece mounting surface of the pallet facing upward by one arm, grip a pallet mounted on the table of the machine tool in a state with the workpiece mounting surface of the pallet facing sideways by the other arm, simultaneously convey the two pallets while changing the orientations of the pallets, and then change the pallets. This pallet conveying robot conveys a pallet to be mounted and dismounted on and from a table of a machine tool, that is, a main pallet, and the workpieces are directly mounted on the main pallets. When a main pallet is large in size or when a main pallet has an angle plate or rotary table mounted on it, even if the workpiece is small in size, the weight conveyed by the robot becomes larger. This being the case, there is the problem that the conveying robot also becomes larger in size.
The prior art described in Japanese Utility Model Publication No. 5-46834 is configured by providing a setup station, which can convey, invert, and rock a main pallet, between a main pallet conveyor system (pallet pool line) attached to a machine tool and a sub-pallet conveyor system making a sub-pallet roll and slide in the horizontal state sub-pallet conveyor line). An angle plate is fixed to the main pallet, the sub-pallet mounting surface of the angle plate is matched in height with the sub-pallet rolling and sliding surface of the sub-pallet conveyor line, and a slide operation is used to dismount an old sub-pallet from the angle plate and mount a new sub-pallet on the angle plate. The main pallet having a new sub-pallet mounted on the angle plate is then inverted and returned to the pallet pool line. This invention conveys the main pallet to the sub-pallet conveyor line and mounts and dismounts sub-pallets on and from the main pallet. This invention is configured such that the sub-pallet just slides on the sub-pallet conveyor line and a setup system conveys, inverts and rocks the main pallet in order to mount the sub-pallet on the main pallet. That is, there is the problem that the setup system becomes large in size.